Advice

[KALM]

not any thing visible

 

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[KALM]

 

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[pedro de pacas]

Got to be a root problem of some sort, only thing i can think of

[merl1n]

Could the stems have grafted to the ground and then when you "rectified" it's caused an issue? Just spitballin

Tunkers may be onto something here.

There are tiny bugs (microbes) in the soil naturally and those bugs will attack the phloem. Those microbes are good bugs that the soil (and the plant need) at the root level, but not so good at stem level. This is why trees etc naturally have a stem/trunk before the start of the canopy.

 

From yr images, in that 2nd image notice the change in that stem colour from the affected stem to the others. That's a definite issue with the phloem layer, otherwise they'd all be the same green.

How to fix? I'd suggest removing the stem personally. I'd be leaving about an inch or 2 of stem above ground level to prevent any further bugs from entering. If you do decide to remove the affected branch, I'd be using something like Clonex over the exposed cut stem. This will seal it from further ground bacteria penetrating the stem, but that's not to say that such bacteria haven't already entered that stem. I know it will be a loss but if an infection progresses you could lose the whole plant.

 

Merl1n

[Tunkers]

Tunkers may be onto something here.

There are tiny bugs (microbes) in the soil naturally and those bugs will attack the phloem. Those microbes are good bugs that the soil (and the plant need) at the root level, but not so good at stem level. This is why trees etc naturally have a stem/trunk before the start of the canopy.

 

From yr images, in that 2nd image notice the change in that stem colour from the affected stem to the others. That's a definite issue with the phloem layer, otherwise they'd all be the same green.

How to fix? I'd suggest removing the stem personally. I'd be leaving about an inch or 2 of stem above ground level to prevent any further bugs from entering. If you do decide to remove the affected branch, I'd be using something like Clonex over the exposed cut stem. This will seal it from further ground bacteria penetrating the stem, but that's not to say that such bacteria haven't already entered that stem. I know it will be a loss but if an infection progresses you could lose the whole plant.

 

Merl1n

Yeah, that's what I said hahaha...

[greenqueen2]

Last time i had borers my big girls went from healthy to laying flat on the ground in about four days with evident stress up top, i went to grab the main trunk and pull it from the ground to see if i could salvage anything but to my surprise there was nothing too pull there was no roots just a stump barely even in the ground hence why they fell over there was no root system to hold them up, dum thing was i had ten plants in that plot and only four out of ten were effected and of couse it had to be the four biggest ones

 

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[loves420]

Have you taken a very close look at the plant. If its the pest I'm thinking and really hoping its not, you'll need a minimum of 14X to see them, some say 20X. You would be wise to also invest in a microscope that magnifies up to 200X, more is better. Because hemp Russel Mites are so small, you might see damage already done on your plant(s) before seeing them (there maybe be thousands of mites on the plant at this point).  They DO NOT make webs. They are white to yellowish-orange, tiny, squirmy, maggoty-looking, and nauseating pests will humble even the most seasoned of growers. Some gov.'s release them.

 

For more information on them https://freemygreenpdx.com/topic/14547-pest-hemp-russet-mite/?tab=comments#comment-130809

[greenqueen2]

Sorry i meant with NO evident stress up top

 

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[loves420]

Keep in mind, I'm in the US so my stuff is based off for northern hemisphere. The European Corn Borer (ECB) and Hemp Borer (HB) are the two most destructive caterpillars. There are few caterpillars cause as much damage as ECBs and HBs.   An exception is the budworm (e.g., Heliothis armigera, Heliothis viriplaca, and Pieris rapae).  Budworms wreck havoc on flowering buds, but leave stems alone.

 

These pests will feed on the centermost part of the cannabis plants’ stalk, the marrow inside the stalk causing stem cankers to form. Starting with the creation of holes within the stem, which also allows an opening for other pests ( bug, mildew, etc.) easy access. This feeding ruptures the plant's support system and eventually causing heavy flowering bud sites to topple over and entire plants to collapse.

 

The hemp borers are almost exclusive host-specific to the Cannabaceae  family. They are known to attack hemp, cannabis, hops, and sometimes knotweed. They are more destructive and can consume an average of 16 cannabis seeds per larva. Because they are so host-specific to cannabis family, anti-cannabis researchers have been flagged as the HB as a potential bio-control agents (using other living organisms to control pests by relying on predation, parasitism, and herbivory) against our cannabis.

 

The best thing to do, especially when problems with stem boring caterpillars occurred in the past, is to be one step ahead, preventing the eggs of butterflies to hatch, and the larvae to consider your plants as a potential nourishment.

 

 

ID for the ECB:

 

Adult: Wingspan of 3/4 to 1¼ inch; female moth are larger than the male moth. Several dark zigzag markings across the wings. The adult moths typically fly at night and are not attracted to light. The adult female is capable of laying up to 2000 eggs per season. Total adult longevity is normally 18 to 24 days. Moths are most active during the first three to five hours of darkness. Dispersal of moths and disruption of moth emergence by heavy rainfall are thought to account for high and variable mortality (68 to 98%, with a mean of 95%), which largely determines population size of the subsequent generation. Overall generation mortality levels were high, averaging 98.7%. Females are strong flyers, seeking host plants to lay eggs. Males are smaller and darker

 

 

http://entnemdept.ufl.edu/creatures/field/european_corn_borer05b.jpg

Female ECB

 

Female moths: thicker body, yellowish buff to light tan wings. both the forewing and hind wing crossed by dark zigzag lines and bearing pale, often yellowish, patches. Wingspan for females 25 to 34 mm. They lay up to 500 eggs in 25 days.  Eggs deposited on lower leaves of the most mature hosts on undersides of leaves, stems, or crop rubble. Eggs laid in groups of 15-50.  Whitish-yellow to translucent eggs overlap like fish scales.   Eggs are less than 1 mm long and 0.75 m in width. As the larvae develop inside their eggs, the eggs become more and more transparent and the immature caterpillar black or brown heads are eventually visible within the creamy white eggs. The caterpillars hatch by chewing their way out of the eggs. The developmental threshold for eggs is about 59F (15°C). Eggs hatch in four to nine days.

 

 

http://entnemdept.ufl.edu/creatures/field/european_corn_borer05a.JPG

Male ECB

 

Male moths: thinner body, The male is darker in color darker; tan-to-grayish brown wings also with dark zigzag lines and yellowish patches. Males measuring 20 to 26 mm in wingspan.

 

 

1st generation larvae over-winter in stalks of host plant, transform into pupae in late April to early June. Adults emerge and lay eggs mid-May to mid-June. Larvae chew holes in leaves, then into stalk, where they pupate. 2nd generation moths emerge in late July to late August. Keep in mind the timing is based for the northwest US.

 

 

The whitish eggs are glued to underside of leaves laid individually or in groups during late summer or early fall in grasses or rolled up plant leaves. They resemble over-lapping fish scales. Eggs will then overwinter and hatch in late April or early May. It can take a period of four to five weeks for all eggs to hatch. Eggs hatch in five to six days (72 degrees to 77 degrees F.), or three to four days (78 degrees to 82 degrees F. Egg mortality (about 15%) was low, stable and due mostly to predators and parasites.

 

http://entnemdept.ufl.edu/creatures/field/european_corn_borer01.jpg

 

http://www.ent.iastate.edu/pest/cornborer/files/styles/media_gallery_thumbnail/public/files/images/eggs-spider-eggcase-12.jpg?itok=C7I297Si

Eggs of ECB

 

Larvae: Young larvae are initially dirty white; color may change to light tan or pinkish gray as larvae mature. 1/3-5/8” in length. Skin is smooth and free of hairs with numerous round dark spots scattered over top and sides with dark head. Four prolegs (3rd, 4th, 5th, 6th and 10th abdominal segments). They are ¾ to 2 inch long ECB larvae are relatively easy to identify because of their distinct coloration. Mortality of young larvae, due principally to dispersal, dislodgement, and plant resistance to feeding was fairly low (about 15%) but more variable.

 

The young larvae feed externally on the host plants, later boring into the stalks, leaves, stems, and ears. Young larvae tend to feed initially within the whorl, especially on the tassel. When the tassel emerges from the whorl, larvae disperse downward where they burrow into the stalk and the ear. Mortality tends to be high during the first few days of life, but once larvae establish a feeding site within the plant survival rates improve.  Young larvae (caterpillars) eat leaves until half grown (through the third instar).
 

 

 

As the larvae mature however, the distinguishing white lines disappear, and the majority of body color turns to a light brown to brownish-gray or pinkish gray in dorsally, with a brown to black head capsule and a yellowish brown thoracic plate. The body is marked with round dark spots on each body segment. The developmental threshold for larvae is about 51F (11°C). Larvae in the final instar overwinter within a tunnel in the stalk of corn, or in the stem of another suitable host. At this later stage they can be confused with both the cutworm. Mortality of large larvae during the autumn (about 22%) and following spring (about 42%) was due to a number of factors including frost, disease and parasitoids, but parasitism levels were low. Mature caterpillars may grow 15-25 mm. long.  Larvae feed for about three weeks, then spin cocoons and pupate.  They spin flimsy cocoons and transform into reddish-brown torpedo shaped pupae (10-20 mm long).  Mature larvae overwinter in crop rubble near the soil line. 

 

They pupae usually occur in April or May (in the US), and then later in the year if more than one generation occurs. The pupa is normally yellowish brown in color. Remains inside host plant; smooth, yellowish- brown to dark brown in color. The pupa measures 13 to 14 mm in length and 2 to 2.5 mm in width in males and 16 to 17 mm in length and 3.5 to 4 mm in width in females. The tip of the abdomen bears five to eight recurved spines that are used to anchor the pupa to its cocoon. The pupa is ordinarily, but not always, enveloped in a thin cocoon formed within the larval tunnel. Duration of the pupal stage under field conditions is usually about 12 days. The developmental threshold for pupae is about 55F (13°C). Pupal mortality (about 10%) was low and stable among generations.

 

 

 

 

Hemp borers arrived in North America around 1943.  Species are differentiated by their genitalia. The hemp borer, are true experts of camouflage, and eggs are hard to spot.

 

http://bugwoodcloud.org/images/768x512/5482461.jpg

 

Adult HB

 

Adults are dark brown with two pair of white dorsal strigulae on each forewing. Hindwings are dark brown. Forewings strongly varying in color from light brownish-ocherous to dark brownish-red. Outer margin of forewing bearing 9 oblique light yellow stripes directed backward. Four slanting light yellow stripes located in the middle of inner margin. Fringe of forewing is dark gray with metallic shine. Hindwings grayish-brown. The adults life less than two weeks.

 

Wing pattern is similar to other Grapholita, especially Grapholita tristrigana in eastern North America. The dorsal strigulae in G. delineana are usually narrow and distinctly separated, while those in G. tristrigana may be confluent. The two species can be separated by genitalia: in G. tristrigana the male aedeagus tapers evenly and females lack a signum in the corpus bursae.

 

Male: Wingspan 11.5 mm. Male genitalia are characterized by an aedeagus that narrows abruptly.

 

Female: Wingspan 15 mm.  Female genitalia are characterized by two signa in the corpus bursae.

 

http://www.biolib.cz/IMG/GAL/161371.jpg

 

Adult HB

 

 

Eggs: Eggs are transparent to white to pale yellow and oval (0.6 mm in length, 0.4 mm. wide) laid singly on stems and leaf undersides. They have thin and wrinkled shell. Females of spring generation lay eggs one by one or by 2-3 on the lower side of hemp leaves (to 60% of eggs), on their upper surface (to 30%), on stalks and petioles (about 10%). Moths of the subsequent generations lay eggs in abundance on inflorescences. Fertility of females of the wintered generation is 100-200 eggs on average, and 350-500 eggs in the subsequent generations. Caterpillars hatch in 8-10 days at temperature 20-22° C. Eggs hatch in 5-6 days at 71-77F (22-25C), or 3-4 days at 78-82F (26-28C). Out of 350-500 eggs, its estimated only 147 larvae survived to first instar. Decrease of humidity to 40% causes death of 80% of eggs.

 

Larvae are similar to those of other Grapholita. An anal comb is absent. Caterpillar light yellow to bright red, 8-12 mm in length, with light yellow-red head. Prothoracic shield light yellow and transparent. Abdominal legs with 16-20 hooks forming a uniserial crown.After hatching, young larvae skeletonize leaves or leaf mine on lower side near ribs. From 2nd instar, they gnaw holes in leaf petioles and in stalks at hemp growth stage of 4-5 leaves for several days before the caterpillars creep upward along stalks, gnawing new holes into petioles, branches and stalks. This feeding within branches and stalks cause fusiform-shaped galls and splitting. Branches and stalks may snap at galls, although the length of tunnels within galls averages only 1 cm or at most 2 cm. Boring near the terminal shoot may kill the shoot and cause branching at that point. Borers pupate within stems. Sometimes 20-50 caterpillars simultaneously feed on one plant. Duration of their feeding is 21-33 days. Caterpillars of summer generation develop one month.

 

http://idtools.org/id/leps/tortai/large/images/Grapholita_prunivora/prunivora_1949057.jpg

 

Pupa light brown, 5-7 mm in length, with 2 rows of spinules directed backward on dorsal side of 2nd-8th segments. Caterpillars of the last (usually 5th) instar winter in the cocoons covered with soil particles and located at roots, in a surface soil layer to a depth of 5-10 cm, within plant residues in fields, in places of thrashing, retting, storing, and also in thickets of wild growing hemp. Larvae pupate in silken loose cocoons covered with bits of hemp leaf.

 

Pupation of caterpillars of summer generations occurs mainly in stalks, seeds, and braided leaves. Development of pupae lasts 16-22 days. some caterpillars pupate in cocoons in ground depending on temperature. Pupation begins at 70F (10.4°C). Late-season larvae pupate in curled leaves within buds, bound together by strands of silk.

 

In warmer regions two or more generations occur per year.  Last-instar larvae that overwintered, pupate in April, in soil under plant debris-crops stubble, weeds, and sometimes stored seed.. Moths of 1st generation fly from early-May to the end of June.  They migrate at night to new hemp fields. Once finding a hemp field, females land quickly, usually within 9.8 feet (3m) from the fields edge. After mating, females lay between 350-500 eggs. Adults live less than 2 weeks. Moths are not strong fliers.

 

Caterpillars of 2nd and 3rd generations gnaw holes in small stalks, eat away buds, flowers, and especially seeds. Second generation from July to the last third of August.  Flight of moths of the 2nd generation coincides with the growth stages of flowering and formation of seeds. The generations overlap, and all stages of the Hemp Moth development meet during the vegetation period. 

 

Caterpillars of the 3rd generation, from the end of August to the last third of September, eat mainly seeds. Having no time to finish their development before harvesting, the usually perish. late-season larvae that hatch in the autumn will feed on leaves, flowers and seeds, hence the common names 'hemp leaf roller' and 'hemp seed eater'. The larvae spin loose webs around terminal buds, especially the seed clusters of female plants. The seed eaters destroy young seeds.

 

The majority of caterpillars diapause by the end of August to October  (for US) under the influence of seasonal change of daylight hours. Day length under 14 hours and temperature influences diapause- warm weather slows photoperiodic effects.   At least 22 hymenopteran species parasitize on the Hemp Moth, killing up to 38.5% of caterpillars and 14.5% of pupae.

 

Stem boring caterpillars do their damage from the inside of the plant so, they can go undetected until it’s too late and the harm is done. Hemp Borer damage often is in the top 1/3 of plants, while European corn borers usually form galls in the lower 3/4 of the plant.

 

ECB and other boring caterpillars drill longer tunnels than hemp borer larvae. Weevils, curculios, and gall midges also bore into stems and form galls. Late-season hemp borers that infest buds may be confused with late-season budworms. They leave an entry hole at the base of the stalk where they continue chewing through the stems of your plant. a brown trail of death will follow the path of the borer. They cause severe enough damage to water transportation systems of plants everything around the trail dies. If the base of branches or the main stem of the plant are infected, death can quickly follow for everything outwards of the trail.

 

It takes about five to ten caterpillars to demolish your plant. What’s even worse is that the hole ECB carve into the stems creates an open doorway for other pests that will complete suck the life out of your cannabis plants.

 

Minor root pests include:

 

Root maggots (Delia platura), The bean seed fly or seedcorn maggot is a small dipterous insect. It is a sporadic pest with cosmopolitan distribution on germinating seeds of many agronomic plants. Also known as the cabbage maggot fly (Delia radicum) and the onion maggot fly (Delia antiqua), but it becomes active earlier. Previous names for this insect include: Hylemya platura, Hylemya cana, Hylemya cilicrura, Hylemya similis and others.

 

It is the most widespread occurring on all continents except Antarctica. They can have up to five generations per year.  The time required to grow from egg to adult is three to four weeks, and a mean temperature of 74 °F (23 °C) for at least 24 to 25 days is required for completion of the life cycle.

 

The eggs are white, elongated, 1/16 in (0.16 cm) long, and deposited in loose groups among the debris and around plant stems near the soil surface. The flies mate within two to three days after emerging, and each female lays an average 50-200 small, white eggs in plant stems right at the soil line or in cracks in the soil near plant stems.

 

The eggs hatch after two to four days at temperatures as low as 50 °F (10 °C). Females lay eggs near food resources. This pest is closely associated with organic matter such as manure and plant residues.

 

The legless larvae (maggots) are dirty white with a yellow tint, cylindrical and tapered in shape. Fully grown maggots are 1/5-1/4 in (0.50-0.63 cm) long and have a pointed head with two black mouth hooks. The abdomen is blunt with two brown to black spiracles at the posterior end. The larval period lasts nearly 21 days. and the maggots develop over a large temperature range: 52 °F to 92 °F (11 °C to 33 °C). They complete their entire development within the soil by burrowing into seeds or feeding on cotyledons emerging from seeds.

 

The pupa are 3/16-1/4 (0.48-0.64 cm) in long, dark brown to black, barrel shaped, and found in the soil near roots. The pupal stage requires at least 10 days until adults are ready to emerge. They survives the winter in the pupal stage in soil, and adults emerge in early spring

 

Adults (1/5 inch long) are brownish-gray to dark gray flies that look like the common housefly with three stripes on their back, only smaller.  hey are half the size of a house fly, approximately 3/16-1/4 (0.48-0.64 cm) in long. Adults are very numerous in the spring (two to three generations), but their population starts decreasing substantially in mid-summer. In the southern United States, adults are found commonly in the fall, early winter, and spring seasons, but few have been reported in mid-summer. adults die when the temperature exceeds 84 °F. hide under wood and other sheltered habitats to avoid high temperatures.

 

Host plants: alfalfa, cotton, strawberry, hemp, cannabis, tobacco, wheat,

 

 

Controlling weeds and grasses in and around the grow site is the most useful preventative measure available. There are two important times when this method is most effective. First, mow or burn surrounding grasses and weeds in mid-August. This will reduce locations for the adults to lay eggs, which overwinter. Another good time to burn down or mow weeds is during the early spring just before eggs hatch. It is important to make sure that eggs have not hatched though because mowing or burning will force the surviving larvae out of the weeds and into the neighboring crops.

 

 

Since the borer lives inside the stalks, it makes sprays nearly useless. Your only chance for this method to work is before they bore, but odds are this window will be missed.

 

Biological control

 

Native predators and parasites exert some effect on European corn borer populations, but imported parasitoids seem to be more important. Birds and small mammals are among the natural predators of the borer. Avian predators such as downy woodpecker, Dendrocopos pubescent (Linnaeus); hairy woodpecker, Dendrocopos villosus (Linnaeus); and yellow shafted flicker, Colaptes auratus (Linnaeus) have been known to eliminate 20 to 30% of overwintering larvae.

 

Insect predators often eliminate 10 to 20% of corn borer eggs.

 

Among the native US predators that affect the eggs and young larvae are the insidious flower bug, Orius insidious (Say) (Hemiptera: Anthocoridae); also known as minute pirate bugs.

 

 

Green lacewings, Chrysoperla spp. (Neuroptera: Chrysopidae)

 

Exotic parasitoids numbering about 24 species have been imported and released to augment native parasitoids. About six species have successfully established. Among the potentially important species is Lydella thompsoni Herting (Diptera: Tachinidae), which may kill up to 30 % of second generation borers in some areas, but has disappeared or gone into periods of low abundance in other areas. Other exotic parasitoids that sometimes account for more than trivial levels of parasitism are Eriborus terebrans Gravenhorst (Hymenoptera: Ichneumonidae), Simpiesis viridula (Hymenoptera: Eulophidae), and Macrocentris grandii Goidanich (Hymenoptera: Braconidae).

 

Many native organisms heavily parasitize the hemp borer larvae in the US. 75% of larvae infested by Lixophaga variablis, a tachinid fly, and Macrocentrus delicatus Cresson, a braconid wasp. Goniozus species attack the hemp borer larvae. Scambus species parasitize 30% of hemp borers.

 

Trichogramma wasps to control the 1st generation with 51-68% efficiency. Parasitic wasps Tachinid, Gymno chaeta ryficornis, Braconids, Apanteus papaipemae and Meteorus leviventris, an Inchneumoid, Lissonota brumnea and a Eulophid, Sympiesis viridula.

 

Caterpillar Parasites (Trichogramma species)

 

 

Chalcid wasps (Chalcidoidea Order Hymenoptera)

 

 

Parasitoid wasp- General/ multiple species

 

 

Predatory nematodes can help control grubs in the soil but this is a preventative measure. You can also try injecting stem galls with nematodes.

 

Spined soldier bugs (Podisus maculiventris).  They preys on young hemp borer feeding on the leaf

 

 

 

 

Hope this helps

 

 

 

[greenqueen2]

Awesome loves420 you may be a yank but you know your shit , thanks for sharing that knowledge with everyone here, great post,,GQ

 

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